And the follow up to that possible theory is that Cap comes back to life and goes on a quest to get another dose of the super soldier serum.
Then he encounters the only human on Earth who has just a tiny bit of the serum left.
Cap has to do this man a favor once it is administered and his abilities return.
This favor is something illegal. He is seen doing this and is branded a villain until he can redeem himself at some point in the future.
"I offer you a Vulcan prayer, Mr Suder. May your
death bring you the peace you never found in
life." - Tuvok.
